This invention relates to projectors, and more particularly to projectors used both as input and output devices.
A projector can be used as a pointing device, a common example being a laser pointer. This allows a user to specify a point, but not to show a track, such as a circle defining a region on a surface. One way to show a track in the prior art is to augment the laser pointer with a fixed camera in the environment, observing the display surface to recover the track of the laser point, and a fixed projector to project a view of the recovered track. Thus the hand-held laser pointer must be augmented with a fixed installation in the environment, and this reduces portability.
A projector can also be used to project augmentation information onto a physical object or surface, as is known in the prior art. Most systems have used some mechanism for identifying an object or surface of interest, some mechanism for finding the relative position between the projector and the object or surface, and have then displayed augmented information. There has been little work on augmentation using hand-held projectors. But as projectors become smaller and portable, many uses of augmentation are likely to arise in opportunistic situations in everyday settings that make use of hand-held projectors, not in fixed installations. Furthermore if augmentation is to be truly flexible, there is a need to control the augmentation. For example when projecting information for a maintenance task onto a machine there may be a series of steps each requiring different projected augmentation, so there is a need for a mechanism to move through the steps, and there may be a need for flexibility in choosing between different steps.
Thus, there is a need to control and interact with projected augmentation from a hand-held projector. To obtain a familiar mode of interaction, the user could use a projector with attached touch-pad, or a thumbwheel, e.g., for 1D selections, and could display for example a menu, and then use the touch-pad to select a menu item, as a way of controlling the augmentation. But this adds expense because the projector must be augmented with a touch-pad. And it adds size. And it may be clumsy or difficult to obtain the required accuracy of positioning the cursor when working with a hand-held device with a small touch-pad.
Therefore, it is desired to provide a hand-held projector that does not have the limitations and problems of the prior art systems. It is desired to have a hand-held projector which not only projects a point, but which can also display a visible track as the user moves the projector. It is also desired to allow the user to interact with augmentation information from a hand-held projector by a mouse-style interaction, in a natural manner with one hand.
An interactive display system includes a sensor for sensing a relationship between a mobile coordinate frame fixed to a moving projector, and a stable coordinate frame fixed to a stationary display surface in the real world.
An output image to be projected on the display surface is partitioned into a black image portion having a fixed relationship to the mobile coordinate frame, a stable image portion within the black portion having a fixed relationship to the stable coordinate frame, and a mobile image portion within the stable portion having a fixed relationship to the mobile coordinate frame.
The black portion has the same outer boundary as the boundary of the fill projector display area. The stable portion appears fixed on the display surface. The mobile portion can be used as a pointer to information within the stable portion.